Ryanair tinkers with its schedule to fit in new flights. They have no plans to add any more based aircraft this year. Other airlines have been able to fit more flights in during slack times on a 'W' basis operating from & to their overseas base. Ryanair and easyJet cannot get any further slots for early morning departures or late evening arrivals. That is how come to that conclusion! In addition Stansted has a cap on the number of movements they can handle.